Recent highlights from atomic force microscopy of DNA

Seven recent highlights are presented from atomic force microscopy (AFM) of DNA in this lab. The first two involve advances in the observation of enzy matic reactions in near-physiological solutions. E. coli RNA polymerase was observed to process along its DNA template in a series of time-lapse image s [S. Kasas, et al., Biochemistry 36, 461 (1997)], and a new small-cantilev er atomic force microscope (AFM) imaged DNA degradation by DNase I at rates as fast as two seconds per image. The next five highlights involve structu ral observations of DNA and DNA-protein complexes, including DNA condensed for gene delivery, sequence-dependent DNA condensation, an AFM assay for RN A polymerase, and AFM evidence for a yeast kinetochore complex that may be involved in holding together sister chromatids during cell division.